Motivations for Searching for Extra Space Dimensions

On behalf on the ATLAS and CMS collaborations The introduction of extra space dimensions in the theory could be an elegant way to solve the hierarchy problem. There could even be one energy scale at which all interactions could unify. The limits coming from our knowledge of the gravitation at low distance allow this energy scale to be as low as few TeV. This situation is extremely interesting experimentally in the context of the LHC which will cover the range from 100 GeV to few TeV. This article describes the different analyses developed by the LHC experiments to study this new phenomenology. The Standard Model of particle physics has a very powerful prediction power but provides no answer to very important conceptual questions related to the deep structure of our universe. A part of these questions concern the relations that exist between the different interactions that we know. Are these forces originating from a unique force which would lead to a Grand Unification Theory (GUT) ? What is exactly the Plank Scale ? Is there a common framework in which all the interactions could be embedded in a self-consistent theory ? What is the exact structure of our space-time and how does it interfere with the particle spectrum that we observe ? Why do various energy scales exist in physics going from 200 GeV for the electroweak scale to 10 19 GeV for the Plank scale ? In the last past years, a new direction 1,2,3,4 has been proposed to explain why gravitation is so weak and why the Plank scale is so large. The new idea is to introduce extra-space dimensions on top of our usual 3 dimensions. These extra-dimensions are not seen at our scale, so they have